1. Field of the Invention
The present invention relates to a current limit circuit apparatus, more particularly to a current limit circuit apparatus for limiting the gate current of the GaN transistor, in order to increase the breakdown voltage of the GaN transistor by limiting the gate current of the GaN transistor.
2. Description of the Prior Art
The GaN is a wide band gap semiconductor with quick switching capability. It is a high-frequency operated electronic device for bringing great change to the communication technology. Except this, it has high breakdown voltage, and it is also one of the best materials for manufacturing of the high-power transistor and will bring the revolutionary change to the high-power device.
The conventional way for increasing the breakdown voltage of GaN transistor is to use different process or change the material of device, the technical level is higher and the cost is also higher. How to increase the breakdown voltage of GaN transistor without changing the process and material has become one of the topics endeavored by the industry.
Please referring to FIG. 1, which shows the relation between the leaking current at the output/input end of AlGaN/GaN transistor and the voltage of drain-source. As shown in FIG. 1, when the AlGaN/GaN transistor is operated at the cut-off region, the leaking current is increased with the voltage difference (Vds) of the drain and the source. When the breakdown voltage is achieved, almost all leaking current of the drain flows to the gate. Upon using the abovementioned feature, when the AlGaN/GaN transistor is turned off and the current flown from the drain to the gate is limited, the breakdown voltage of GaN transistor will be increased.
Therefore, a current limit circuit apparatus coupled with the gate of a GaN transistor is required to limit the current flown out of the gate, in order to increase the breakdown voltage of GaN transistor.